Except for MMORPGs that are neary assumed to come out in "beta" status, if a game comes with bugs, it gets hammered by reviews (you have the recent Demigod example with multiplayer). It doesn't matter it gets great after several patches, the damage to the game for the general opinion is already done.
The games initial release is important, but game patches play a huge role because all games have major bugs causing not only crashes, but even permanently stuck where the only way out is starting over. The quality of patches not only improve stability, but some even add game content.
Also, there's a big difference in patches and mods (comparing them is like comparing apples and oranges): usually patches are applied automatically for the game, that's something a non-technical person can do, while mods have to be searched, downloaded and installed.
patches applied automatically?? Only if you're buying a game several months or years after it's release! For patches players need to visit the official website; download the game patch then install the game patch and periodically checks the forums to verify the new patch doesn't bring any new issues. For game mods the player visits the official forums for reviews; download the game mod then installs the game mod and periodically checks the forums for any related issues. Both of the processes are virtually identical.
Of course, the world is full of opinions, but there's a general consensus by RPG players that BG/Torment are better RPGs than NWN (even if Torment was a comercial disaster). Some people may disagree, but that always happens.
That's nothing but an opinion with no evidence for support.
And if you don't like it, search for NWN 2 interviews, they say most times that their objective is to have a deeper/better/whatever story in single player, that speaks volumes. It also speaks volumes that DA:O is considered by Bioware the spiritual succesor to Baldurs Gate, and not to NWN.
I never said the NWN singleplayer was better than Baldurs Gate, only it has greater replay value. Of course if I could only play one RPG game for three times then it would be BaldursGate2. However anyone who could only play one RPG game for the rest of their life would choose Neverwinter Nights because of the unlimited replay value. Heck given most of us will be around for another 20+ years I tend to be more pleased with a game which provides endless replay value as compared with a one_time fixed world.
Your bet. BG2 and Torment are classics, people will keep playing them for a long time. I don't think that will happen with NWN.
Compare the forum activity for Neverwinter Nights against BG2 or Torment and neither even comes close. It's the endless replay value within Neverwinter Nights which will keep it going for a long long time. I seriously wish the BG2 provided an editor OR a random game generator because then it would replay value beyond its fixed world where all the quests, towns, traps, bosses, NPCs, etc, are all the same.
